I. Field of the Invention
The present invention relates generally to integrated circuit technology. More specifically, the invention relates to a multi-chip system which includes a chip carrier having a multi-layered metallized through-hole interconnection and a method of making the same.
II. Description of the Related Art
There is a growing desire for a xe2x80x9csystem on a chipxe2x80x9d as integrated circuit technology enters the ultra large scale integration (ULSI ) era. Ideally, the industry would like to build a computing system by fabricating all the necessary integrated circuits on one substrate, as compared with today""s method of fabricating many chips of different functions on multiple substrates. The concept of xe2x80x9csystem on a chipxe2x80x9d has been around since the very large scale integration (VLSI) era (early 1980s), but even today, it is very difficult to implement such a truly high-performance system on a single chip because of vastly different fabrication processes and different manufacturing yields for various logic and memory circuits. With many diverse circuits, especially with a mixture of analog and digital circuits, a low-impedance ground is also required to suppress digital noise. High-speed synchronous digital integrated circuits require large switching currents which can induce noise on the power distribution networks and ground busses due to finite resistance and inductance in these circuits. Additionally, power supply noise can have a tremendous effect due to simultaneous switching noise in CMOS integrated circuits. These problems are more severe in mixed-mode analog/digital circuits and require careful design of the power distribution systems. Thus, based on current circuit implementation, there is a need for a built-in ground plane adequate to handle and dissipate noise which is also difficult to fabricate on a single chip with other components. A buried ground plane is highly desirable to provide a flat surface to which various chips, active circuits, and passive components can be subsequently mounted.
To overcome some of these problems, a xe2x80x9csystem modulexe2x80x9d has recently been suggested in T. Mimura, et al, xe2x80x9cSystem module: a new Chip-on-Chip module technology,xe2x80x9d Proc. of IEEE 1997 Custom Integrated Circuit Conf., pages 437-442, 1997. This system module consists of two chips with a first chip stacked on a second chip in a structure called Chip-on-Chip (COC) using a micro bump bonding technology (MBB). With this technology, each chip can be fabricated to perform specified functions with optimum processing conditions. Then the individual chips can be combined in a single packaged structure.
Recently, in U.S. patent application Ser. No. 09/144,307, by Ahn et al., a compact system module with built-in thermoelectric cooling is described in which a memory chip is directly mounted on a microprocessor chip. In U.S. patent application Ser. No. 09/144,290, by the same inventors of the ""307 application, a scheme of high-performance packaging in which individual chips are mounted on a silicon interposer is described. In another U.S. patent application Ser. No. 09/143,729, a built-it cooling channel was introduced for efficient removal of heat generated by many chips mounted on a silicon interposer. Furthermore, a silicon interposer with built-in active devices was also recently disclosed in U.S. patent application Ser. No. 09/144,197. Still further, an attempt to assemble a compact system using multi-chip module technology for space-borne applications is disclosed by R. J. Jensen et al., in xe2x80x9cMission: MCM, Designing for Reliability in Harsh Environments,xe2x80x9d Advanced Packaging, January, 1998, p. 22-26, in which decoupling capacitors are an integral part of the system. Davidson et al. in an article entitled xe2x80x9cLong Lossy Lines and Their Impact Upon Large chip Performance,xe2x80x9d IEEE Trans. On Component Packaging and Manufacturing, Pt. B., vol. 20., no. 4, p. 361-375, 1997, addresses key concerns in assembling many chips to a system module, namely, the length and resistance of the interconnect lines. Davidson, cites an example of a single microprocessor chip partitioned into four smaller ASIC chips for higher production yield and consequently lower cost, and suggests mounting them on a single multichip module, called a die pack, such as illustrated here in FIGS. 1(a) and 1(b). With such a scheme, a long data line can be reduced to a few millimeters. Also, see U.S. patent applications Ser. Nos. 09/009,791, 09/199,442, 09/247,680, 09/258,739 and 09/255,077 for related discussions on mounting individual chips on a common carrier substrate.
While many improvements have been made in the multi-chip on a substrate technology, there still remains a need for a high performance compact system which provides controlled low-impedance wiring, including the ground and distribution plane wiring, between chips mounted on the same and opposite side of a common substrate.
The present invention is directed to an apparatus and method of making an apparatus for a high-performance system module which uses multi-layer metallized through-hole interconnections on a chip carrier substrate to provide short wiring and controlled low-impedance wiring between chips mounted on the carrier, the wiring including at least one of a ground plane and a power distribution plane.
The term xe2x80x9csubstratexe2x80x9d used in the following description may include any semiconductor-based structure that has an exposed silicon surface. Structure must be understood to include silicon-on insulator (SOI), silicon-on sapphire (SOS), doped and undoped semiconductors, epitaxial layers of silicon supported by a base semiconductor foundation, and other semiconductor structures. The semiconductor need not be silicon-based. The semiconductor could be silicon-germanium, germanium, or gallium arsenide. When reference is made to substrate in the following description, previous process steps may have been utilized to form regions or junctions in or on the base semiconductor or foundation.
The inventive method of the present invention comprises providing a chip carrier substrate, typically formed of silicon, with a multi-layer metallized through-hole interconnection. The through-hole interconnection may be formed by: depositing a first insulating layer of silicon dioxide over a substrate; depositing a first ground plane or power supply plane layer over the silicon dioxide layer; depositing a second insulating layer over the first layer; depositing a signal line wiring layer over the second insulating layer; depositing a third insulating layer over the signal line wiring layer; depositing another (second) ground plane or power supply plane layer over the third insulating layer; and depositing a fourth insulating layer over the second ground plane or power supply layer. The carrier substrate can be used to carry and interconnect one or more chips as part of an integrated package unit.